In paint application systems wherein liquid paint is applied to an article, a paint circulation system is used to deliver paint to the applicator and to prevent liquid paint from settling or coagulating. The paint circulation systems generally rely on pumps to circulate the liquid paint through a piping loop. While several different types of pumps can be used to circulate the paint, the present disclosure is principally concerned with pneumatic and hydraulic pumps.
Pneumatic pumps are powered by compressed air originating from a compressed air source and directed to the pump. The compressed air directed to the pump causes the pump to stroke. The output of the pump, measured herein as a number of strokes/minute, is directly proportional to the pressure of the compressed air supplied to the pump. As the pressure of the compressed air supplied to the pump increases, the output of the pump increases, and vice-versa. Hydraulic pumps operate on a similar principle, replacing compressed air with pressurized fluid.
Accordingly, by controlling the pressure of the compressed air (or fluid for a hydraulic pump) delivered to the pump, the output of the pump can be controlled. Circulation pump control systems typically operate at the same setting all the time, regardless of whether they are delivering paint (in a production state) or not (in a non-production state.